Method and Apparatus For Charging Batteries

ABSTRACT

A method and apparatus for charging batteries includes using an input rectifier to receive an ac input and provide a dc signal. A converter receives the dc signal and provides a converter output. An output circuit receives the converter output and provides a battery charging signal. A controller preferably controls the converter to power factor correct. The system can include multiple output circuits, used either singly or at the same time, and designed for one or more voltages. They can be user removable. Preferably, the converter output has a magnitude independent of a range of frequencies and a range of magnitudes of the ac input, and the range can be, for example, at least a factor of two or at least two utility voltages. The controller includes a charging schedule module that receives feedback, such as voltage and/or current feedback and/or temperature feedback. The output circuit, such as a dc-dc converter, is controlled in response to the feedback in other embodiments. The battery type may be sensed or input by a user, and the charging done in response to the battery type. A defective battery sensor is preferably included, with a user-noticeable indicator.

FIELD OF THE INVENTION

The present invention relates generally to the art of battery charging.More specifically, it relates to battery charging using versatilecircuitry that can preferably receive multiple inputs and/or providemultiple outputs.

BACKGROUND OF THE INVENTION

There are a large number of rechargeable batteries having a wide varietyof voltages and charging schedules. (Charging schedule, as used herein,is the manner in which the charging is performed for a given battery.For example, one charging schedule might call for a limited amount ofcurrent initially, and then a greater current when the battery voltagecrosses a threshold, followed by a trickle charge after the batteryvoltage crosses a second threshold.) It is typical that a charger bedesigned for a single battery type, and have a single output voltage andcharging schedule. Of course, dedicated battery chargers are notversatile, and can require a facility to have a number of chargers.

Other chargers are not dedicated, but are “dumb” chargers that apply aconstant voltage output with the charging current being controlled bythe load, not the charger. These chargers might work for any battery ofa given voltage, but do not optimally charge batteries. Thus, if suchchargers are used to charge several batteries simultaneously, theycannot provide a unique charging current or voltage for each battery.Rather, a single charging schedule is used for all batteries beingcharged. This also diminishes the usefulness of chargers.

Some battery chargers are inefficient because they have a poor powerfactor. This causes increased costs when power is utility power, and canlessen the charging capacity, particularly when using generator power.The use of generator power can cause another problem—generators oftenprovide “dirty” power, i.e., power that is not perfectly sinusoidal, ornot of a constant value. Dirty power can result in improper charging.

Prior art battery chargers are often design for a single input voltageand frequency. While this might be sufficient for consumer batterychargers, some applications, such as industrial battery charging, orautomotive charging, might be used at different locations where theinput power is not the same.

Rechargeable batteries have a finite life, in that their ability to becharged diminishes over time. Often, a user finds the battery is nolonger chargeable by charging it, then using it, and having the batterybecome discharged in a short period of time.

Accordingly, a battery charger that is versatile enough to chargedifferent types of batteries, or to simultaneously charge batteries withdifferent outputs, is desirable. A modular design, where output circuitsfor particular batteries can be switched in and out by the user, is onemanner to allow different charging schedules. Also, a single outputmodule could be used for any battery type, where the user selects thebattery type, or the charger senses the battery type. Preferably, such acharger will provide power factor correction, and be able to receive awide range of inputs. Also, it will preferably be able to receive dirtypower, and still charge a battery. A charger that provides the user awarning when a battery is defective is also desirable.

SUMMARY OF THE PRESENT INVENTION

According to a first aspect of the invention a battery charger andmethod of charging a battery include using an input rectifier to receivean ac input and provide a dc signal. A converter receives the dc signaland provides a converter output. An output circuit receives theconverter output and provides a battery charging signal. A controllercontrols the converter to power factor correct.

According to a second aspect of the invention a battery charging systemand method includes an input circuit that receives an input signal andprovides a dc signal. A plurality of user-removable output circuits aredesigned to receive the dc signal and provide a battery charging signalat a desired voltage and a desired current, and only one of the outputcircuits is connected at a time. A controller, controls the connectedoutput circuit.

According to a third aspect of the invention a battery charging systemand method includes an input circuit that receives an input signal andprovides a dc signal. A plurality of output circuits are connected atthe same time, and receive the dc signal and provide a battery chargingsignal at a desired voltage or voltages and a desired current orcurrents. A controller provides a control signal to each of the outputcircuits.

The converter output has a magnitude independent of a range offrequencies and a range of magnitudes of the ac input in onealternative.

The converter output has a substantially constant magnitude for a rangeof inputs spanning at least a factor of two or at least two utilityvoltages in various embodiments.

The controller includes a charging schedule module. The chargingschedule modules receives voltage feedback and/or current feedback. Theoutput circuit is a dc-dc converter controlled in response to thefeedback in other embodiments.

The controller includes a battery selection input, and controls thecharger in response to the battery selection input. The selection inputis responsive to a user-selection, or a wired or wireless battery typesensor, such as an RFID sensor, in various embodiments.

The output circuit is designed for a particular battery voltage and theoutput circuit may be removable in another embodiment.

Additional output circuits, for the same or different voltages, and foruse one at a time, or a plurality at a time, and user removable orfixed, are provided in various embodiments.

The converter may be a boost converter, a buck-boost converter, and acombined rectifier boost converter in various alternatives.

The output circuit may be a switched converter, a pulse width modulatedinverter, a pulse width modulated forward converter, or a frequencymodulated in other embodiments.

A defective battery sensor module receives current, voltage ortemperature feedback and determines if a battery is defective isprovided in another embodiment. A user-noticeable indicator is providedwhen a defective battery is detected.

Power for the controller is derived independent of the input in anotherembodiment.

Other principal features and advantages of the invention will becomeapparent to those skilled in the art upon review of the followingdrawings, the detailed description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a battery charger in accordance with thepreferred embodiment;

FIG. 2 is a circuit diagram of a preregulator in accordance with thepreferred embodiment;

FIG. 3 is a circuit diagram of an alternative preregulator in accordancewith the preferred embodiment;

FIG. 4 is a circuit diagram of an alternative preregulator in accordancewith the preferred embodiment;

FIG. 5 is a circuit diagram of an output circuit in accordance with thepreferred embodiment;

FIG. 6 is a circuit diagram of an output circuit in accordance with thepreferred embodiment;

Before explaining at least one embodiment of the invention in detail itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting. Like referencenumerals are used to indicate like components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention will be illustrated with reference to aparticular battery charger and particular circuitry, it should beunderstood at the outset that the invention may also be implemented withother circuitry, software and arrangements.

Generally, the invention is implemented by a battery charger thatreceives an input, such as an ac input, and provides a dc chargingoutput. Preferably, the battery charger may receive any input over arange of inputs without being reconfigured (i.e., re-linked orre-wired), and may be capable of receiving “dirty” power, such as thatfrom a generator. Also, the battery charger preferably includes anoutput stage that can either provide a number of voltages for chargingdifferent batteries, any voltage, or be designed for a single voltage.There can be a plurality of user-removable output stages. When theoutput circuits provides a single voltage, or a narrow range of voltagesfor charging one battery voltage, it is said to be designed for aparticular battery voltage. In one embodiment a number of output stagesare provided, each for charging one battery, wherein the batteries areof the same type or of different types.

When the output circuit is capable charging different battery types, theuser can set the battery type or voltage, or the charger can include asensor. The sensor could be wired (i.e., connected to the battery andeither sense an ID signal, or sense the voltage of the battery), orwireless, such as an RFID sensor to sense an RFID tag on a battery. Thecharger preferably includes a controller that causes the output tofollow a charging schedule based on the battery type and/or voltage.

Another feature the charger preferably has is a “bad” battery detector,wherein the controller senses that a battery is not properly charging.The user is notified of the bad or defective battery. Anotheralternative provides a polarity detector to prevent damage to thebattery and/or charger if the battery is connected with the wrongpolarity.

The power provided for battery charging is not always ideal utilitypower, but might be “dirty” generator power. The present invention canprovide a battery charger that is capable of running off a generatorsource (as well as a utility source). A capacitor or other energystorage device delivers energy to a dc bus in such a way as to reducethe impact of dirty power on the charging circuit and allows forcharging during heavy loading of the generator source.

One advantage of the preferred embodiment is that it will operate usinga wide range of input powers, and thus is well-suited for applicationsor users that use the charger in multiple locations. Various embodimentsprovide for an input range of at least a factor of 2, at least twoutility voltages (115-230V, or 100-256V e.g.), 120V to 525V, or 100V to633V. The preferred embodiment is relatively lightweight, adding to thecharger portability. Additionally, the power circuit does not need to bere-linked or reconfigured by the user for different powers, thus thereis less of a need to open the housing.

The details of the preferred embodiment will be provided below, but theygenerally include a rectifier, followed by a boost converter or abuck-boost converter, followed by a dc-dc converter, such as a pulsewidth or frequency modulated inverter or forward converter. A controllercontrols the boost converter to provide a dc bus having a desiredmagnitude, regardless of the magnitude and frequency of the input(within ranges), and to actively power factor correct the input. Thecontroller also controls the dc-dc converter using feedback of thebattery charging signal. Battery charging signal, as used herein,includes the signal used to charge the battery. For example, thecharging current is controlled using a current feedback loop. A voltagefeedback loop may be used to stop the charging process, or to change toa trickle charging mode. Controller 110 may use functions of the currentand/or voltage feedback and/or temperature feedback, such as power,energy, and integrals and derivatives of the output parameters. Whilethe feedback signals are typically indicative of a magnitude, thecontroller may be responsive to the signal by using a function of thevalue fedback.

When using the features described above, a versatile charger may be madethat is capable of receiving a wide range of inputs, and charging a widerange of batteries, having a number of voltages. For example, multipleoutput stages may be provided and each run off the common bus. Eachoutput stage may be controlled independently of the others, to chargeeither the same type of batteries, or different batteries, either one ata time, or a plurality at a time.

Referring now to FIG. 1, a block diagram of a preferred embodiment of acharging system 100 is shown. Charger 100 includes a preregulator 102, aplurality of output circuits 104, 106, and 108, a controller 110, andfeedback lines/control inputs 112-120 that cooperate to charge batteries105, 107 and 109. While the embodiment illustrated includes three outputcircuits, other embodiments include fewer (including just one) outputcircuit, or many more output circuits. In various embodiments outputcircuits 104, 106 and 108 are fixed in place, or user interchangeable oruser-removable. Controller 110 may be located on a single board ordispersed among several boards. It may be particularly useful todisperse controller 110 among several boards, one in a housing with thepreregulator, and one with each output circuit, when the output circuitsare user-removable.

User-removable, as used herein, includes a portion of the system beinghoused in such a way as the user can remove it and replace it withrelative ease. For example, batteries on cordless power tools areuser-removable, as are batteries in automobiles. Depending upon theapplication and sophistication of the user, more or less effort by theuser is required to remove the output circuit.

The preferred embodiment provides that preregulator 102 includes a fullor half-bridge rectifier (input circuit) and a boost or buck-boostcircuit. Examples of such circuits are shown in FIGS. 2 and 3. Theiroperation is well known, and won't be described herein but a boostcircuit can increase an input voltage to a desired magnitude, and abuck-boost circuit can increase or decrease an input voltage to adesired magnitude. In various embodiments the rectifier is omitted (fordc inputs, e.g.), or combined with the boost circuit, such as shown inFIG. 4. Combined rectifier-boost, as used herein, includes a circuitsuch as FIG. 4, where the rectifier is part of the boost circuit.

Preregulator 102 receives an ac input and provides a dc bus. AC input,as used herein, includes any utility, generator, or other ac signal. Theinput can be of a different type, such as dc, in other embodiments. If adc input is used, a rectifier is not needed. The signal that causes theswitch in the boost or buck-boost converter to change states is receivedon a control input (an input for control rather than power signals). Theoperation of the preregulator results in a dc bus that is has amagnitude independent of the input magnitude, and is dc, independent ofthe input frequency. Thus, the input signal may have any frequency andmagnitude within a range of magnitudes and a range of frequencies, andpreregulator 102 will still provide the desired dc bus.

Alternative embodiments include other preregulator switched converters,such as a buck, SEPIC, or CUK converter. Converter, as used herein,includes a power circuit that receives or provides an ac or dc signal,and converts it to the other of an ac or dc signal, or to a differentfrequency or magnitude.

Controller 110 preferably controls the preregulator to be power factorcorrected to improve efficiency. The power factor correction is active,in that the controller switches the boost switch 203 to increase thepower factor. The power factor correction may be accomplished using apower factor correction circuit 204 (located in controller 110), such asan off the shelf integrated circuit that provides power factorcorrection for boost circuits.

The output of the preregulator is a dc bus at a voltage controlled bycontroller 110. The preferred embodiment provides that the converteroutput (a dc bus) be controlled to have a voltage of 950V regardless ofthe input voltage or frequency. Other bus voltages may be used.

Controller, as used herein, includes digital and analog circuitry,discrete or integrated circuitry, microprocessors, DSPs, etc., andsoftware, hardware and firmware, located on one or more boards, used tocontrol a device such as a preregulator, power circuit, or outputcircuit. Controller 110 receives power from a controller power sourcewhich may be a separate transformer based source, battery, or the dcbus.

The dc bus is maintained at a substantially constant voltage (there maybe ripple voltage or other voltage perturbations that do not adverselyimpact performance) by capacitors 206 (which may be implemented with oneor more capacitors). The invention contemplates that “dirty” power mightbe used to charge batteries. Thus, the capacitance is selected toovercome the problems caused by dirty power.

Over time, the energy provided by the generator source must be greaterthan the energy used to charge the batteries. However, for lengths oftime on the order of the period of the input power the charging energymaybe greater than the generator-provided energy. DC bus capacitors 206have a capacitance, according to the present invention, sufficient toprovide the difference between needed output power when and theavailable generator power. In the preferred embodiment, dc bus capacitor206 can store an amount of energy equal to the energy (over time)available in approximately 2.75 cycles of the input signal, or in otherwords, an amount of energy equal to approximately E=2.75(P)(T) joules,where P is the maximum output of the charger (combined for all outputcircuits) and T is the period of the generator ac signal. This overcomesthe transients that occur in the input power which are typically on theorder of a cycle T in length. In alternative embodiments of the presentinvention, capacitor 206 can store an amount of energy at least equal tothe energy (over time) available in at least 1.5 cycles of the inputsignal (or in other words, E=1.5(P)(T)), in at least 2 cycles of theinput signal (E=2(P)(T)), or in at least 2.5 cycles of the input signal(E=2.5(P)(T)).

Thus, the capacitance of capacitor 206 is C=5.5(P)(T)/(V²), where V isthe bus voltage for E=2.75(P)(T), or energy for 2.75 cycles, andC=3(P)(T)/(V²), where for 1.5 cycles, and C=4(P)(T)/(V²), for 2 cyclesand C=5(P)(T)/(V²) for 2.5 cycles.

In the preferred embodiment, the approximate values of P, T, and V are:P=1250 watts, T=16.67 milliseconds (or 20 msec for 50 Hz), and V=950volts. This results in a capacitance value for capacitor 206 of at least127 microfarads in the preferred embodiment, and capacitance values ofat least 70 microfarads, at least 92 microfarads, and at least 115microfarads, for the various equations for C described above.

Referring now to FIGS. 5 and 6, example of preferred output circuits 104and 106 are shown. The embodiment shown in FIG. 5 is a pulse-widthmodulated inverter, and the embodiment of FIG. 6 is a forward converter.The general operation of both circuits is well known. Other embodimentscontemplate frequency modulation and/or other output converters,particularly converters that switch a signal applied to a transformerprimary, and provide the output through the transformer secondary,thereby isolating the input and output.

The embodiment of FIG. 5 includes an inverter that, for example, invertsthe 950 v bus through the primary of transformer 505. The secondary ofcenter-tapped transformer 505 is rectified and the dc signal is providedto charge the battery. Controller 110 modulates the pulse widths toprovide a desired output. Various embodiments include full or halfbridge topologies, or other topologies. The signal used to pulse widthor frequency modulate or otherwise control the load current and/orvoltage may be called a load control signal. The preferred outputcircuits are easily controlled to provide any output voltage. Thus, theymay be used for any type of battery within a range, so long as thebattery is identified (by the user or sensed, e.g.), and a chargingschedule is available for that battery. Also, the preferred outputcircuits may be dedicated to a single battery voltage and/or type, forexample by including control circuitry with the output circuit.

In one embodiment, a portion of controller 110 is included in thehousing that houses output circuit 104, and monitors the output currentto provide a desired charging current, in accordance with a chargingschedule provided by a charging schedule module 502 (which is part ofcontroller 110). Module, as used herein, includes software and/orhardware that cooperates to perform one or more tasks, and can includedigital commands, control circuitry, power circuitry, networkinghardware, etc. A charging schedule module is a module that provides acharging schedule.

Charging schedule module 502 includes a current module responsive tocurrent feedback and a voltage module responsive to voltage feedback inthe preferred embodiment. The current feedback may be considered part ofan inner control loop. Voltage feedback is used in an outer controlloop, to determine when the battery is nearly charged, and when thebattery voltage crosses a threshold, the charging current is greatlyreduced to a trickle charge. Other embodiments provide for monitoringthe battery temperature, and reducing charging current based ontemperature. The charging schedule can include any needed feature, suchas an initial slow charge, a discharge mode, a trickle charge, etc.Integrated circuits that provide a charging schedule are commerciallyavailable.

The housing containing output circuit 104 may also include a batterysensor 504, which is part of controller 110 and senses battery 105, andprovides a signal indicative of the battery type and/or voltage tocharging schedule module 502. Battery sensor 504 may be wired orwirelessly connected to battery 105. A wired connection allows batterysensor 504 to determine the battery voltage and/or type from the batteryterminals, or from a separate terminal on the battery which providesinformation of voltage and/or type. Battery sensor, as used herein, is asensor that determines battery type and/or voltage. The battery sensorcan be part of controller 110, or part of the output circuit.

A wireless connection is made when the battery has a wirelesstransmitter which transmits information of the battery type and voltage.One such wireless system is an RFID (radio-frequency identification)system. An RFID tag which transmits information is placed on thebattery, and sensor 504 includes an RFID receiver which receives theinformation. The information transmitted and received can be similar to“bar code” information, or it can be more or less complex. Sensor 504 isan optical bar code reader, a WIFI receiver, a magnetic strip reader orother wireless reader various embodiments. Controller 110 includes abattery selection input that receives the information from the sensor.Battery selection input, as used herein, includes any input thatreceives information, sensed or provided by the user, of battery voltageand/or type. The charging schedule module is responsive to batteryselection input, in that the charging schedule is chosen or modifiedbased on the battery type.

The battery type and/or voltage is provided on a user-selectable input,such as a panel knob, button or selector, or by instructions sent on bypda, computer, wireless controller, etc. in various embodiments to thebattery selection input on controller 110. User-selectable input, asused herein, includes any input sent from the user, either locally orremotely.

According to various embodiments each output circuit is designed for aparticular battery type and/or voltage. The output circuits may bepermanently fixed or user removable. Thus to charge a 12 volt automotivebattery the user selects the 12 volt output circuit, or automotivebattery output circuit, and connects it to the preregulator. Similarly,to charge a 24 volt battery, the user connects the 24 volt outputcircuit to the preregulator. Preferably, the connection involvessnapping a housing into place, wherein an electrical connection and astructural connection is made. For example, a portable power toolbattery is connected to the tool to make both an electrical and astructural connection.

The invention contemplates multiple output circuits connected to apreregulator at one time, as shown in FIG. 1. In such an embodiment,each output circuit includes its own control circuitry (that is part ofcontroller 110) to provide the required output (which can be sensed,set, or fixed as described above). Each output circuit receives the dcbus and inverts or converts it to its particular desired output. Thevarious output circuits may be identical or different and may providethe same or different outputs.

As described above, charging current and voltage (and batterytemperature in some embodiments) is provided to controller 110. Thatinformation, or other battery characteristics, is used, in variousembodiments, to determine whether a battery is defective (cannot beproperly charged), either because it has reached the end of itsrecharging life or perhaps because of a manufacturing defect or it hasbeen damaged. Temperature can be directly monitored or remotely sensed,such as by an infrared sensor, for example.

Controller 110 includes a defective battery sensor module 506 detects adefective battery by comparing the a battery characteristic such ascurrent and/or voltage and/or temperature to a known profile. If thecharacteristic deviates beyond a threshold, controller 110 determinesthe battery is defective. For example, some charging schedules providefor trickle charging batteries having a voltage below a threshold. Ifthe trickle charging fails to raise the voltage above a threshold, thatbattery is deemed defective. The components and or software used todetect the inability to properly charge are referred to as a defectivebattery sensor module.

When controller 110 determines a battery is defective it activates auser-noticeable output 508 such as a warning light, audible alarm, aninstant message sent remotely or an email message. The warning can besent by a wired connection or a wireless connection. User-noticeableoutput, as used herein, includes a warning indicator on a housing (suchas on the housing for the output circuit or the preregulator), or amessage sent to a telephone, pda, computer, remote indicator, etc.

Numerous modifications may be made to the present invention which stillfall within the intended scope hereof. Thus, it should be apparent thatthere has been provided in accordance with the present invention amethod and apparatus for battery charging that fully satisfies theobjectives and advantages set forth above. Although the invention hasbeen described in conjunction with specific embodiments thereof, it isevident that many alternatives, modifications and variations will beapparent to those skilled in the art. Accordingly, it is intended toembrace all such alternatives, modifications and variations that fallwithin the spirit and broad scope of the appended claims.

1.-55. (canceled)
 56. A battery charging system, comprising: an inputcircuit, configured to receive an input signal and to provide a first dcsignal; a plurality of user-removable output circuits, each configuredto receive the first de signal and each designed to provide a batterycharging signal at a desired voltage and a desired current, wherein achosen one of the plurality is connected at a time; and a controller,configured to provide at least one control signal to the chosen oneoutput circuit.
 57. The battery charging system of claim 56, wherein theinput circuit includes a rectifier and a boost converter or a buck-boostconverter, and further including an input controller that provides powerfactor correction.
 58. The battery charging system of claim 57, whereinthe first dc signal has a substantially constant magnitude and the rangeof magnitudes spans a range of at least a factor of two.
 59. The batterycharging system of claim 56, wherein the controller includes a chargingschedule module and receives at least one of a voltage feedback signalindicative of the voltage magnitude of the battery charging signal and acurrent feedback signal indicative of the current magnitude of thebattery charging signal.
 60. The battery charging system of claim 59,wherein the controller includes a battery selection input, and whereinthe charging schedule module is responsive to the battery selectioninput.
 61. The battery charging system of claim 60, wherein the batteryselection input is connected to a user-selectable input.
 62. The batterycharging system of claim 60, wherein the battery selection input isconnected to a battery sensor.
 63. The battery charging system of claim62, wherein the battery sensor includes an RFID sense circuit disposedto be sense an RFID tag on a battery being charged.
 64. The batterycharging system of claim 59, wherein the output circuit includes aswitched converter.
 65. The battery charging system of claim 59, whereinthe switched converter is a pulse width or frequency modulated inverter.66. The battery charging system of claim 59, wherein the switchedconverter is a pulse width or frequency modulated forward converter. 67.The battery charging system of claim 59, wherein the controller includesa defective battery sensor module that receives as an input a second atleast one of the voltage feedback signal and the current feedbacksignal, and provides a user-noticeable output indicative of a defectivebattery.
 68. A method of battery charging, comprising: converting aninput signal to a first dc signal; and selecting one of a plurality ofuser-removable output circuits, each designed for a battery voltage, andusing the selected output circuit, changing the first dc signal into asecond de signal having a current suitable for battery charging.
 69. Themethod of claim 68, wherein converting includes boost converting andpower factor correcting such that the first dc signal has a magnitudeindependent of a range of magnitudes of the input signal.
 70. The methodof claim 69, wherein the first dc signal has a substantially constantmagnitude and the range of magnitudes spans a range of at least a factorof two.
 71. The method of claim 68, further comprising controlling acharging current in response to at least one of a voltage feedbacksignal and a current feedback signal.
 72. The method of claim 71,wherein the controlling a charging current is responsive to auser-selectable input.
 73. The method of claim 71, wherein thecontrolling is responsive to sensing a battery to be charged.
 74. Themethod of claim 73, wherein sensing includes sensing an RFID tag on thebattery.
 75. The method of claim 73, wherein converting includes one ofbuck-boost converting and boost converting.
 76. The method of claim 75,wherein changing includes switching a converter.
 77. The method of claim76, further comprising monitoring a battery for being capable of beingcharged properly, and providing an indication if the battery cannot becharged properly.
 78. A battery charging system, comprising: convertermeans for receiving an input signal and providing a converter output;and a plurality of user-removable output means for receiving theconverter output and providing a battery charging signal, wherein eachoutput means is further for providing the battery charging at a desiredvoltage, wherein a selected one of the plurality is connected to theconverter means at one time.
 79. The battery charging system of claim78, further comprising an output control means for controlling theselected one output means, connected to the selected one output means.80. The battery charging system of claim 79, further comprising aconverter control means for controlling the converter to provide powerfactor correction and to provide the converter output at a desiredvoltage, and connected to the converter.
 81. The battery charging systemof claim 80, wherein the converter means includes one of a boost and abuck-boost converter, and wherein the converter output has a magnitudeindependent of a range of magnitudes of the input signal.
 82. Thebattery charging system of claim 41, wherein the output control meansfurther is for controlling a charging current in response to at leastone of a voltage feedback signal and a current feedback signal.
 83. Thebattery charging system of claim 82, wherein the output control means isresponsive to a user-selectable input.
 84. The battery charging systemof claim 78, further comprising means for sensing a battery to becharged, and controlling the charging current in response thereto. 85.The battery charging system of claim 84 wherein the means for sensing abattery includes means for sensing an RFID tag.
 86. The battery chargingsystem of claim 84, wherein each output means includes a dc-dcconverter.
 87. The battery charging system of claim 84, wherein eachoutput means includes a pulse width or frequency modulated inverter. 88.The battery charging system of claim 84, wherein output means includes apulse width or frequency modulated forward converter.
 89. The batterycharging system of claim 84, further comprising means for monitoring abattery for being capable of being charged properly, and providing anindication if the battery cannot be charged properly.
 90. A batterycharging system, comprising: an input circuit, configured to receive aninput signal and to provide a first dc signal; a plurality of outputcircuits, each configured to receive the first dc signal and eachdesigned to provide a battery charging signal at a desired voltage and adesired current, and a controller, configured to provide at least onecontrol signal to each of the plurality of output circuits.
 91. Thebattery charging system of claim 90, wherein the input circuit includesa rectifier and a boost converter or a buck-boost converter, and furtherincluding an input controller that provides power factor correction. 92.The battery charging system of claim 90, wherein the controller includesa battery selection input, and wherein a charging schedule module isresponsive to the battery selection input.
 93. The battery chargingsystem of claim 92, wherein the battery selection input is connected toa battery sensor.
 94. The battery charging system of claim 93, whereinthe battery sensor includes an RFID sense circuit disposed to be sensean RFID tag on a battery being charged.
 95. A method of batterycharging, comprising: converting an input signal to a first dc signal;and using a plurality of output circuits, each designed for a batteryvoltage, to change the first dc signal into a plurality of charging dcsignals suitable for battery charging.
 96. The method of claim 95,wherein converting includes boost converting and power factor correctingsuch that the first dc signal has a magnitude independent of a range ofmagnitudes of the input signal.
 97. The method of claim 96, wherein thecontrolling is responsive to sensing a battery to be charged.
 98. Themethod of claim 97, wherein sensing includes sensing an RFID tag on thebattery.
 99. A battery charging system, comprising: converter means forreceiving an input signal and providing a converter output; and aplurality of output means for receiving the converter output andproviding a plurality of battery charging signals.
 100. The batterycharging system of claim 99, further comprising an output control meansfor controlling the plurality of output means, connected to each of theplurality of the output means.
 101. The battery charging system of claim100, further comprising a converter control means for controlling theconverter to provide power factor correction and to provide theconverter output at a desired voltage, and connected to the convertermeans.
 102. The battery charging system of claim 99, further comprisingmeans for sensing at least one battery to be charged, and controlling acharging current in response thereto.
 103. The battery charging systemof claim 102 wherein the means for sensing a battery includes means forsensing an RFID tag.